Manufacture of artificial textile materials



Patented Jan. 16, 1940 MANUFACTURE F ARTIFICIAL TEXTILE MATERIALS Albert Mellor, Spondon, near Derby, England, as-

signor to-Celanese Corporation of America, a corporation of Delaware No Drawing. Application January 22, 1938, Serial No. 185,315. In Great Britain February 4 Claims.

This invention relates to improvements in the manufacture of artificial textile materials, and particularly to the production of textile mates 'rialshaving an improved extensibility.

i It has been discovered that fabrics having an improved extensibility may be obtained by subjecting fabrics containing superficially saponified yarns of cellulose acetate or other organic ester of cellulose to treatment with a medium con- 0 taming a shrinking agent for the organic ester of cellulose in the absence of tension suiilcient to stretch the fabric.

, It appears that the surface layers of cellulose or of cellulose ester of low acyl value protect the yarns and render it possible to obtain the desired increase in extensibility without the material assuming such a softened state that subsequent manipulation is rendered difllcult or impossible. -In order to obtain the best results with the minimum loss of acyl content it is, therefore, important that the saponiilcation should be so far as possible superficial. For this purpose saponifying agents such as sodium and potassium hydroxides and sodium carbonate have been 25 found to be most suitable. Good results may be obtained with such agents when a superficial saponiflcation has been effected which reduces the average acetyl value of cellulose acetate yarns .to about 45 to' 50% (i. e., about 1.8-2.1 acetyl 30 groups per CcHmOs unit) and the average acyl value of other cellulose ester yarns to an equivalent amount,- calculated in terms of the ester groups per CsHmOs unit. The saponiflcation of p the yarn may be effected either before or after 36 the formation of the fabric.

. The shrinking agents which have been found to give the best results are water-soluble agents, for example acetone, dioxane and ethylene methylene ether, though'watereinsoluble agents, for 4 example methylene and ethylene dichlorides, may be employed. Water-soluble agents are preferably employed in aqueous solution, e. g., in a concentration of 45-65%, while agents such as methylene dichloride may be dissolved in benzene, carbon tetrachloride or other suitable liquid. Swelling agents such as methylene and ethylene .dichlorides may be employed in conjunction with liquids such as alcohols which increase their a swelling action, but care should be taken that the proportions are not such that the mixture has a solvent action on the materials.

The treatment is preferably eflected at about atmospheric temperature, e. g., 15, 20 or 25 C.,

55 though a higher or lower temperature may, if

desired, be employed, e. g., a temperature of 5 or 10 C. or of 40 or 50 C. I

The concentration of the shrinking agent is preferably adjusted so that in the case of a woven fabric a warp shrinkage of about 10 or up to about or is obtained. Thus, for example, a cellulose acetate fabric containing yarns which have been saponifled to an average acetyl value of about i5 to 48% may be run through a pad mangle containing a 60 to 65% aqueous solution I" of acetone at about 12 to 20. C., the nip of the mangle being adjusted to give about 70 to 80% expression. From the mangle the fabric may be run direct to a pin stenter. A fabric in which the warp shrinkage is about 20% and the weft l5 shrinkage about 4-6% may thus be obtained.

The following examples illustrate the invention, but are not to be regarded as limiting it in any way:

Example 1 20 A cellulose acetate crepe-de-chinefabric suit,- a-bie for underwear is secured and then saponifled to an average acetyl value of 48% by treating it-with a 1% aqueous-solution of sodium carbon 05 ate at about'70" O. for about 1% hours, the volume ratio being :1. The fabric after dyeing and drying is then shrunk by padding it through a 65% aqueous solution of acetone at 18 0., the degree of expression being about 70%. One dip 30 and one squeeze are given and the fabric is then fed direct to a pin-stenter for The stenter is adjusted to run' 25% slower than the fabric speed through the mangle to allow the necessary shrinkage to take place, and the width of the stenter is arranged so that the fabric is slack during the whole of the drying. The temperature of drying may be varied to suit the .length. of the stenter employed and the speed of drying. A' suitable temperature is about 65' 0.

Example 2 A saponiiied and dyed fabric, such as is treated according to the preceding example, isshrunk by treatment with a 55% aqueous solution of seetone for about V minute at .15 to 20C. The

fabric is supported and carried forward through the shrinking medium by anv endless calico band. and on emerging from the solution it is passed into another bath: where it is well washed with water. At this .stage the degree of shrinkage is approximately 10% warp and 2% weft. The

fabric is thenslack dried on an endless band conveyor wherefurther shrinkage occurs, the final shrinkage being about 20% warp and 5% weft. The productsobtained accordingto either of the preceding examples have an improved extensibility.

The expression superficially saponified yarns". as employed hereinafter in the claims, is to be construed as meaning yarns which have a saponified surface of lower acyl value surrounding a core which is unchanged, i. e. unsaponified, organic ester of cellulose.

Having described my invention, what I desire to secure by Letters Patent is:

1. Process for the production of artificial silk fabrics having an improved extensibility, which comprises treating fabrics containing superficially saponified yarns of organic esters of cellulose which have an average acyl content of about 1.8 to 2.1 groups per 'CsHmOs unit with aqueous solutions of organic liquids having a solvent or swelling action on the organic esters in the absence of tension sufiicient to stretch them.

2. Process for the production of artificial silk fabrics having an improved extensibility, which comprises treating fabrics containing superficially saponified yarns of cellulose acetate which have an average acetyl content of about 1.8-2.1 groups per CcHioOs unit with aqueous solutions of or- ,ganic liquids having a solvent or swelling action on the acetate in the absence of tension suflicient to stretch them.

3. Process for the production of artificial silk fabrics having an improved extensibility, which comprises superficially saponifying yarns of organic esters of cellulose with sodium carbonate to form products having an average acyl content of about 1.8 to 2.1 groups per CoHiuOt unit and treating fabrics containing such superficially sa ponified yarns with aqueous solutions of organic liquids having a solvent or swelling action on the organic esters in the absence of tension suflicient to stretch them.

4. Process for the production of artificial silk fabrics having an improved extensibility, which comprises superficially saponifying yarns of cellulose acetate with sodium carbonate to form products having an average acetyl content oi about 1.8 to 2.1 groups per CsHmOa unit and treating fabrics containing such superficially saponified yarns with a 55 to 65% aqueous solu-- tion of acetone in the absence of tension sufficient to stretch them.

ALBERT MELLOR. 

